Refining of mineral oils



'INVENTOR Feb. 22, 1938. M. T. KENDALL v REFINING OF MINERAL OILS l'Filed Jan. 13, 1934 Patented Feb.` 22, 1938 REFINING OF MINERAL OILS Marcus T. Kendall, Long Beach, Calif., assignor to The Texas Company, New York, N.

corporation of Delaware Application January 13, 1934, Serial No. 706,482

2 Claims.

This invention relates to the manufacture of a kerosene or burning oil, and particularly to the refining thereof by distillation and chemical treatment.

from a crude or other petroleum oil In the manufacture of burning oil, also termed lamp oil or kerosene, it is customary to distil of! a kerosene fraction of the wide boiling range desired in the ultimate product. This kerosene distillate is then subjected to a refining treatment with chemicals,

such as fuming sulphuric acid, to remove aromatic and sulphur hydrocarbons, and refined oil of satisfactory burn test, or will give comparatively long service produce a one which in a lamp tities of refining agents are used.

One of the objects of the present invention is to provide a method of producing a marketable burning oil of this character while effecting a very substantial economy in the use agents.

of refining Other objects and advantages of the invention will be apparent from the following description when taken 1n conjunction with the accompanying drawing and appended claims.

According to the present invention,

the refining of the kerosene hydrocarbons is carried out by a so-called split stream treatment, in which the hydrocarbons of the kerosene range are divided into a lighter fraction and a he avier fraction, and the different kerosene fractions separately refined with an effective refining agent,

such as fuming sulphuric acid. It has heretofore been suggested to refine cracked gasoline by a split stream method, but the purpose and operation are essentially different.

In the case of the cracked gasoline, the lighter fraction contains a substantial proportion of unsaturated hydrocarbons which are anti-detonating purposes, and which desirably retained for Would be removed by a rigorous refining agent. The reaction between a refining agent, such as sulphuric acid, and the hydrocarbons of stantial heat by exothermic reaction,

unsaturated and aromatic a cracked gasoline produces subsuch that a loss in more volatile constituents of the gaso- Consequently,

lighter fraction line results. method of treating a gasoline with only a treating a heavier the split stream of cracked mild alkaline reagent, while fraction of cracked gasoline with sulphuric acid followed by neutralization, and then blending the treated fractions, has been proposed. So far as I am aware, it has not been heretofore recognized that beneficial results and very substantial economy in the use of refining. agent are obtained by split stream treatment of hydrocarbons of the kerosene range.

I have discovered that the amount of refining agent, .such as fuming sulphuric acid, can be reduced as much as 30% to 40% by weight, by sub-dividing the kerosene hydrocarbons into controlled lighter and heavier fractions, and separately treating each fraction with a strong refining agent of the same or similar character. It is well known Ythat kerosene fractions contain substantial percentages of aromatic and sulphur hydrocarbons, and that a rigorous refining treatment is necessary to remove these objectionable constituents and produce a kerosene having a good burn test. The percentages of aromatic and sulphur hydrocarbons increase with rise in boiling points of the kerosene hydrocarbons. Consequently, a fraction boiling between 350- 435 F. does not contain as large a quantity of aromatic and sulphur hydrocarbons as a fraction boiling between 435-550 F. However, both fractions contain these objectionable constituents 25 and require the use of the same type of vigorous refining agent in their removal. I have found that it is of distinct advantage to treat the lighter kerosene fraction with a relatively small quantity of the effective refining agent, and the heavier kerosene fraction with a substantially larger quantity of the refining agent in a concentratedKV manner. In such event, the combined amounts of the refining agent employed in treating the separated fractions are less than the amount of 3 the same refining agent required to treat a mixture of the two kerosene distillates to an equivalent burn test. Following the separate refining of the kerosene fractions, they are then blended to produce a burning oil of the boiling range desired.

In a specific embodiment of the present invention, a crude petroleum oil, or other petroleum oil containing kerosenehydrocarbons, is heated in a tube still to a temperature of about 500- 650 F., and then flashed into a fractionating tower provided with steam stripping and reflux return so that adequate fractionation is effective in securing sharp cuts. The top temperature of the fractionating tower is controlled to condense the kerosene hydrocarbons, and perhaps a heavier gasoline fraction, in the upper portion of the tower. Two separate kerosene fractions of different boiling range are removed as side streams from the tower. Theseseparated fractions are then separately refined and later blended in the manner above described.

Referring to the drawing, in which the single gure is a diagrammatic illustration of a preferred form of apparatus for carrying out the method of the present invention, a conventional tube still is indicated at I0 having a heating coil I I to which a crude oil, or other petroleum oil containing kerosene hydrocarbons, is supplied by a pump (not shown) through the pipe I2. The confined stream of oil is heated under pressure to a temperature which is suiiiciently elevated to effect vaporization of the kerosene hydrocarbons when flashed at a lower pressure into the fractionating tower I4, which may be maintained substantially at atmospheric pressure. Where a crude oil is being treated, this may be the first stage of a two-stage atmospheric-vacuum treatment, wherein the oil is heated in the first stage to a temperature of about 500-650 F. and then flashed into an atmospheric fractionating tower where gasoline, kerosene and gas oil distillates are obtained. Residuum from the atmospheric tower then passes to the second stage where the oil is heated in a second tube still (not shown) to a higher temperature and then flashed into a vacuum fractionating tower (not shown) where lubricating fractions are removed.

As shown, the heated oil passes by pipe I5 containing pressure reducing valve I6, and is discharged into an intermediate zone of the fractionating tower I4, which may contain a plurality of superposed trays I1 of the conventional bubble cap type. A portion of the oil flashes into vapor which passes upwardly through the tower, the unvaporized oil flowing downwardly from tray to tray counter-current to stripping steam introduced at I8, and residuuin escapes from the base of the tower by the valve controlled line I9. Vapors escape from the top of the tower by line 20 to a partial condenser 2I lcooled by any suitable means to a controlled top temperature to effect a partial condensation to provide reflux which is returned to the tower by the line 22. Any excess over the reiiux requirements passes to storage by the branch line 23, and uncondensed vapors pass by line 24 to additional condensing equipment (not shown).

Any suitable number of trays I1 may be provided within the fractionating tower, and all or any number of the trays equipped with liquid withdrawals for side stream removal. As shown, four valve controlled pipes 26-29 are arranged at various elevations along the height of the tower. A gas oil distillate may be removed by the line 29, and a heavy gasoline distillate by the line 26. In place of removing a single kerosene fraction by an intermediate side stream, two separate distillates consisting essentially of hydrocarbons boiling within the kerosene range are removed by the lines 21 and 28 respectively. It is Vto be understood that the positioning of the side streams 21 and 28 coupled with the reuxing within the tower may be so controlled as to ob- ,tain fairly sharp cuts of any desired and variable boiling ranges, whereby a lighter kerosene fraction is removed at 21 and a heavier kerosene fraction at 28. If desired, either or both of the separate kerosene fractions may be further treated with steam in kerosene strippers (not shown) to increase the sharpness of the cuts.

'Ihe separate kerosene fractions are delivered to storage tanks 30 and 3I respectively. The light kerosen'e fraction is passed from storage tank 30 through line 32 containing pump 33 toa refining apparatus indicated diagrammatically at 34. Ihe heavy kerosene ydistillate is passed through line 36 containing pump 31 to a relining apparatus 38. The refining apparatus for each fraction may be of any suitable conventional construction, either adapted for batch or continuous operation. As shown, an agitating tank is illustrated adapted to be supplied with chemical through line 4I from branch lines 42 and 43. Each refining tank is also provided with a sludge withdrawal line 44. 'Ihe kerosene fraction is here treated with a strong refining chemical adapted to remove aromatic and sulphur hydrocarbons. Very satisfactory results are secured where the kerosene fraction is first agitated with fuming sulphuric acid, allowed to settle, the sludge withdrawn; and then to remove products of sulphonation the treated oil is agitated with weaker sulphuric acid, such as recovered sulphuric acid obtained from the fuming acid sludge. The treated oils are then withdrawn, for example, by the line 46 in the case of the lighter distillate from tank 34, and by the line 41 in the case of the heavier distillate from tank 38. 'Ihe treated oil from each tank may then be passed to a second tank where it is treated with alkali, or any other refining treatment desired, such as contact filtration. As this is entirely conventional procedure, involving the use of conventional apparatus, no attempt has been made to illustrate the particular apparatus employed, which may vary widely in construction. 'I'he additional refining apparatus, if such is employed, is connected to the lines 46 and 41, at the points indicated by the breaks therein. If desired, the alkali treatments may be carried out in the same tanks 34 and 48 used for the acid treatments.

The rened light kerosene distillate then passes by line 50 to either a valve controlled branch pipe 5I leading to a suitable storage receptacle or valve controlled line 52 leading to a blending tank 53 having outlet 54. 'I'he heavy kerosene distillate passes by line 55 to either a valve controlled line 56 leading to a storage tank or valve controlled line 51 emptying into the blending tank 53. The two kerosene distillates are mixed in predetermined or controlled proportions in the blending tank 53 to produce a burning oil of the desired character and test.

By way of example, the refining treatment of a Los Angeles basin crude to produce a kerosene or burning oil boiling between 360-485 F., and which meets the required 18 hour burn test, is herein described. In conventional practice, wherein the entire kerosene cut boiling within the range specified is treated with acid, it is found necessary to apply 18 pounds of 15% fuming sulphuric acid per barrel of oil, followed by '7 pounds of recovered sulphuric acid H2SO-4) per barrel. In accordance with the present invention, this kerosene distillate is split into two streams 21 and 28 in the manner previously described. The lighter distillate preferably has a boiling range between 360-435 F., and represents approximately 50% by weight of the entire kerosene distillate of the desired boiling range obtainable from the fractionating tower. 'I'he heavier kerosene fraction boils between 435- 490 F., and represents the other 50% of the kerosene distillate. 'The light distillate is then treated with approximately 4 pounds of 15% iurning sulphuric acid and approximately 9 pounds of recovered acid per barrel. The heavy kerosene distillate, which contains a larger proportion of the aromatic and sulphur hydrocarbons, is severely treated with approximately 20 pounds of 15% fuming sulphuric acid and approximately pounds of recovered sulphuric acid per barrel. This gives a net consumption on the total kerosene distillate of approximately 12 pounds of fuming sulphuric acid and 7 pounds of recovered acid per barrel, thereby effecting a saving of approximately 33.3% of fuming sulphuric acid over that used in the conventional treatment. The light and heavy cuts, after treatment, are then blended in the proportion of their production, which is about 48% by weight of the heavy kerosene distillate to 52% by weight of the light kerosene distillate. This is found to produce a burning oil of the desired boiling range between BGN-485 F., and which has a burn test at least equivalent to that formerly produced by treating the entire kerosene cut with the substantially larger quantity of acid specified above.

It is believed that this greater eiciency of the refining acid in the split stream treatment is due to the following reasons, although I do not wish to be bound thereby. First, the light kerosene distillate contains a smaller proportion of the aromatic and sulphur hydrocarbons and therefore requires less acid for refining to a good burn test. Second, the heavier kerosene distillate contains the larger proportion of the aromatic and sulphur hydrocarbons, and therefore requires the larger proportion of the refining acid. Third, the heavier distillate receives a more concentrated treatment, due to the fact that there is a greater concentration of acid to aromatic and sulphur hydrocarbons. In other words, the light kerosene fraction acts in the nature of a diluent, thus diluting the refining acid and reducing its eciency, so that normally a larger quantity of acid is required to effect an equivalent rening action. The more concentrated treatment of the present invention is responsible for more efficient sulphonation of the aromatics and polymerization of the sulphur hydrocarbons, whereby a smaller quantity of acid is more efficiently utilized. Finally, by splitting the kerosene distillate into two streams as specified, a larger proportion of acid on the weight of the oil treated thereby, can be utilized for the heavier fraction, and still obtain the net saving in acid for the treatments of both fractions. In this manner, a more economical sulphonation and polymerization with fuming sulphuric acid is accomplished by removing that part of the chain of hydrocarbons of lower boiling point that contains less of the undesirable hydrocarbons, and concentrating the treatment upon that part which requires a substantial refining.

It is to be understood that the proportions into which the kerosene stream is split can be varied widely, and still obtain the advantages of the present invention. Further, the invention is not limited to the use of any deiinite quantity or kind of refining agent. For example, other rigorous refining agents may be employed with benecial results in accordance with the principles set forth above, such agents including sulphur trioxide, liquid sulphur dioxide, metallic chlorides such as aluminum chloride, zinc chloride and the like.

Obviously many modifications and variations of the invention, a s hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. The process of preparing a marketable burning oil consisting essentially of hydrocarbons of the kerosene range boiling between substantially 360-490 F., which comprises' separating from a petroleum oil by non-cracking iiash distillation a lighter kerosene distillate fraction boiling between substantially 360435 F. and a heavier kerosene distillate fraction boiling between substantially 435-490 F., treating the lighter kerosene fraction with substantially 4 pounds of fuming sulphuric acid per barrel of oil followed by treating with substantially 9 pounds of recovered sulphuric acid per barrel of oil, treating the heavier kerosene fraction with substantially 20 pounds of fuming sulphuric acid per barrel of oil followed by treating with substantially 5 pounds of recovered sulphuric acid per barrel of oil, and blending the treated kerosene fractions to produce without redistillation a burning oil of the desired boiling range having a burn test at least equivalent to that produced by treating a mixture of the said kerosene fractions with substantially 18 pounds of fuming sulphuric acid per barrel of oil followed by substantially 7 pounds of recovered sulphuric acid per barrel of oil, whereby a substantial saving in the consumption of fuming sulphuric acid is effected.

2. The process of preparing a maketable burning oil from a. crude mineral oil of the character having substantial quantities of aromatic hydrocarbons throughout the kerosene boiling range, which comprises heating a confined stream of the mineral oil to a temperature not substantially exceeding 650 F. but which is sufficiently elevatedto vaporize kerosene hydrocarbons with a portion at least of the gas oil content, flashing the heated oil into a fractionating zone where gasoline vapors are removed overhead and kerosene distillates are removed as side streams, reuxing the vapors in the fractionating zone to obtain sharp cuts, removing from different levels of the fractionating zone .separate side streams each consisting of hydrocarbons of the kerosene range, an upper side stream being a lighter kerosene distillate fraction having a boiling range of the order of S60-435 F. and a lower side stream being a heavier kerosene distillate fraction having a boiling range of 435-490" F., separately treating the said kerosene fractions with predetermined amounts of fuming sulfuric acid capable of removing aromatic hydrocarbons followed Without intermediate distillation by treatment with recovered sulfuric acid to remove products of sulphonation, the said lighter kerosene fraction being treated with a relatively smaller quantity and the said heavier kerosene fraction being treated with a relatively larger quantity of the fuming sulfuric acid, and blending Without redistillation the separately treated kerosene fractions to produce directly a burning oil having a boiling range of the order of 360-485" F.,

'the' fractionation into sharp cuts being predetermined in accordance with the fuming acid requirements of the said separated kerosene fractions to produce after recombining of the treated fractions a blended burning oil having a burn test at least equivalent to that produced by treating the entire kerosene content without splitting thereof with a substantially greater quantity of fuming sulfuric acid than the combined amountsv of fuming sulfuric acid employed in treating both of the separated kerosene fractions such as to produce a net saving of fuming sulfuric acid of the order of 30% or more.

MARCUS T. KENDALL. 

